Problem: Which of the following numbers is a factor of 64? ${5,8,11,13,14}$
Answer: By definition, a factor of a number will divide evenly into that number. We can start by dividing $64$ by each of our answer choices. $64 \div 5 = 12\text{ R }4$ $64 \div 8 = 8$ $64 \div 11 = 5\text{ R }9$ $64 \div 13 = 4\text{ R }12$ $64 \div 14 = 4\text{ R }8$ The only answer choice that divides into $64$ with no remainder is $8$ $ 8$ $8$ $64$ We can check our answer by looking at the prime factorization of both numbers. Notice that the prime factors of $8$ are contained within the prime factors of $64$ $64 = 2\times2\times2\times2\times2\times2 8 = 2\times2\times2$ Therefore the only factor of $64$ out of our choices is $8$. We can say that $64$ is divisible by $8$.